Alienware X51 vs. Dell OptiPlex 5090 M
Comparison and Differences
Differences between Alienware X51 and Dell OptiPlex 5090 M
If you are looking for a more modern desktop, then you should go with the Dell OptiPlex 5090 M which was released in 2021. The Alienware X51 is older and entered production in 2011.
If you are looking for the smaller form factor the Dell OptiPlex 5090 M is the right one for you. It is smaller than the Alienware X51 and will fit more easily under your desk.
Processor
Usually the newer the generation of the CPU, the better the performance and efficiency is. If your budget allows it, you should go with the Dell OptiPlex 5090 M as it is running a newer generation CPU. This is not to say that Alienware X51 is bad - it can still run some powerful CPUs, albeit being an older generation.
Memory
Both models have have equal amount of ram slots (2 RAM). Usually two RAM slots are more than enough for most cases. However, the count should be taken into account when planning how much and what combination of RAM you are going to need for your system.
The Dell OptiPlex 5090 M is using the faster 3200 MT/s RAM. The Alienware X51 is slower by supporting RAM speeds of up to 1333 MT/s. Additionally, if you will be needing a lot of RAM, better go for the Dell OptiPlex 5090 M as it has the ability to run 64 GB of RAM. The Alienware X51 can do a bit less at max 8 GB. Most of the times, this should be sufficient for the majority of users.
Ports
In total the Alienware X51 has 8 USB ports. The Dell OptiPlex 5090 M is inferior in this regard and packs 6 USB ports. In any case, if you miss USB ports, you can always purchase a USB hub. What is nice about the Dell OptiPlex 5090 M, is that it has 1 USB 3.1 port(s) which allows transfer of up to 10Gb/s. Unfortunately, the Alienware X51 has no such port, thus restricting your transfer speeds significantly. For people who want to use external drives on regular basis, this might be an issue.
Unfortunately, only the Dell OptiPlex 5090 M has a DisplayPort. The Alienware X51 does not have one? Don't worry though, nowadays video adapters are cheap and you can get almost any combination of conversion types.
The Alienware X51 comes with an HDMI port, while the Dell OptiPlex 5090 M does not support the interface. Of course missing HDMI port is something that can be easily fixed with a good adapter (e.g. DisplayPort to HDMI).
SATA ports are placed on the system board and it is where you connect your HDD, SSD and Optical Disk Drives. More SATA slots will allow you to have more drives running at the same time. In this regard the Alienware X51 is better equipped as it comes with 4 SATA slot(s), while the Dell OptiPlex 5090 M has 3 slot(s).
If you want the fastest transfer speeds for your SSD, an M.2 interface is crucial. Thus, if the M.2 SSD slot is a mandatory requirement for you, go with the Dell OptiPlex 5090 M. Sadly, the Alienware X51 has no such slot, and you will be forced to use the SATA interface instead.
Make sure that the available M.2 slot supports the PCIe (also called NVMe) interface. This is important as there are M.2 slots which support only the inferior SATA III interface. For comparison, the SATA III interface has max speeds of 6Gb/s, while the PCIe 3.0 x4 will support speeds up to 32Gb/s!
Power Supply
Having a Power Supply Unit with high power rating is important, if you are going to use components which require extra power. The Dell OptiPlex 5090 M comes with a decent 130 Watt PSU, but the Alienware X51 has a more powerful one rated at 330 Watts. Choosing either one depends on your specific requirements and use case. Also don't forget that some models might have more than one PSU option - try to always get the most powerful one, especially if you plan to upgrade to a powerful GPU.
Motherboard
